Multi-Input Multi-Output (MIMO) is a technology that uses multiple transmission antennas and multiple reception antennas to improve transmission and reception efficiency, emerging from the technology that uses a single transmit antenna and a single receive antenna. When a single antenna is used, the receiving side receives data through a single-antenna path. However, when multiple antennas are used, the receiving side receives data through multiple paths. Thus, MIMO can increase transfer rate and the amount of transmission and can also increase coverage.
Single-cell MIMO modes may be divided into a Single-User-MIMO (SU-MIMO) mode in which a single user equipment receives a downlink signal from a single cell and a Multi-User-MIMO (MU-MIMO) mode in which two or more user equipments receive a downlink signal from a single cell.
Studies are being vigorously conducted on a Coordinated Multi-Point (CoMP) system that applies advanced MIMO transmission in multi-cell environments to improve throughput of a user located at a cell edge. Application of the CoMP system can not only reduce Inter-Cell Interference (ICI) in a multi-cell environment but can also improve overall system performance.